This invention relates to contact ultra-sonic probe holders and is suitable for the ultra-sonic inspection of components having irregular surface geometry.
For inspections of this kind it is often desirable that the ultra-sonic beam travels into the components in a direction which is independent of the shape of the surface under the probe holder. This situation arises in the case of the inspection of a weld formed when a circular pipe is joined by welding with a circular vessel, the axes of pipe and vessel being at right angles. Welds of this form appear in the nuclear art. The probe holder also has application in the inspection of other complex welds.
It is an object, when inspecting pipe/vessel welds, to direct an ultra-sonic beam from a probe in a direction so that the line of the beam (when projected) intersects the axis of the pipe. The direction of the beam is then such as to make a right angle with the circumferential direction vector at the weld at all positions in the weld. If the probe is mounted on a gimbal holder or universal joint arrangement (see for example GB-PS-No. 1404471) so that the surface of the probe remains in contact with the surface of the vessel, and the holder is mounted at the end of an arm which rotates about a point on the axis of the pipe which lies inside the vessel then at four angles of rotation only of the arm (namely 0.degree., 90.degree., 180.degree. and 270.degree. ) does the projected beam intersect the axis of the pipe. At other angles the required intersection is not attained.